aacenc: mark the "faac"-like coder for removal

This coder produces a much lower quality audio than the rest, is much
slower and is unstable. Hasn't been updated for a very long time as
well, hence it is more appropriate to remove it since it also depends on
a big burden of a code (the encode_window_bands_info function which is
just as old, just as unstable and bad and in no way modifiable or
fixable).
Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>

libavcodec/aacenc.c

@@ -967,6 +967,8 @@ static av_cold int aac_encode_init(AVCodecContext *avctx)
     s->coder = &ff_aac_coders[s->options.coder];
 
     if (s->options.coder != AAC_CODER_TWOLOOP) {
+        WARN_IF(s->options.coder == AAC_CODER_FAAC,
+                "The FAAC-like coder will be removed in the near future, please use twoloop!\n");
         s->options.intensity_stereo = 0;
         s->options.pns = 0;
     }